At a given temperature, a first-order reaction has a rate constant of 3.5 ´ 10–3 s–1. How long will it take for the reaction to be 24% complete?

Question

A chemical reaction that is first-order in X is observed to have a rate constant of 2.20 ´ 10–2 s–1. If the initial concentration of X is 1.0 M, what is the concentration of X after 186 s?

Answer 1

ln(No/N) = kt
No = 100
N = 100-24 = 76
k from the problem
Solve for t in seconds.

#2
Same equation. Different substitutions and solve for N
Post your work if you get stuck.

Answer 2

In[100/76] = 3.5x10^-3 . t
thus T = 7.84x10^-5

Answer 3

23hr